Electronic cigarettes have recently emerged as a new product for providing nicotine through a smokeless inhalation process. Typically, implementations consist of a power supply (typically a battery) and an atomizing device. In reusable electronic cigarettes the two items are separated into a battery and a cartomizer, to allow the disposal and replacement of a nicotine containing fluid cartomizer while preserving the more costly battery and associated circuitry (microcontroller, switch, indicating LED, etc.) for additional use. In disposable electronic cigarettes, the two items are combined to integrate the functions into one unit that is discarded after either the battery energy or the nicotine containing liquid is exhausted.
The electronic cigarette liquid used to vaporize ingredients such as nicotine is generally a solution of propylene glycol (PG), vegetable glycerin (VG), or polyethylene glycol 400 (PEG400), as well as their mixtures to which a flavor and/or nicotine has been added. The solution is often sold in a bottle (for refilling by the user) or in disposable cartridges or cartomizers. Many different flavors are incorporated into these liquids, including those that resemble the taste of regular tobacco, menthol, vanilla, coffee, cola and/or various fruits. Various nicotine concentrations are also available, and nicotine-free solutions are also common.